Power systems: research
trends and future
Assoc. Prof. Nesimi ERTUGRUL
E’mail: nesimi@eleceng.adelaide.edu.au
Phone: 8303 5465
University of Adelaide
School of Electrical and Electronic Engineering
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
Power systems
• cover a wide range of diverse applications,
• display distinct electrical behaviors,
• are usually inter related, and
• imply highly nonlinear operating characteristics.
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
In power systems ...
•
•
•
•
There is the necessity of electrical isolation and the requirements for the
wide frequency bandwidth measurements (resulting in significant
restrictions on the accuracy of measurements.
When considering a sensor, its characteristics needs ot be assessed based
on three primary criteria: frequency bandwidth, magnitude of the output
signal and electrical isolation.
The frequency bandwidth of measured signals in power systems usually
covers a very wide range (from dc to 10s of kHz).
A conventional voltage transformer may be sufficient to provide a good
electrical isolation amplifiers used to measure high voltages) should also
be considered in the calibration tests. It is desirable to make the calibration
test for each measurement channels.
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
Power systems : the main quantities
The table given below summarise the main quantities that can be
measured in power systems with their associated characteristics.
Quantity
Device
Voltage
Differential amplifier
Typical
Bandwidth
For high voltage measurements, DC to MHz
but not real electrical isolation
Safe high voltage
measurements
DC - 50 kHz
Detects magnetic field produced 50 kHz
by current, available in clamp
type or through-hole
Typical Input
Range
600V
Typical Output
Gain
100V = 1V
1000V
100V = 1V
10A
10A = 1V
Rogowski coil
With a flexible cord suitable for few kHZ
measuring large diameter cables
and rotating shafts.
1000A
100A = 1V
Flux
Search coil
Measures flux produced by 10 kHz
currents such as the current
flowing in the stator and rotor
end-windings
1V
Proportional to
the number of
turns
Vibration
Speed
Piezoelectric accelerometer
Tacho-meter
Acceleration measurements
Measures shaft speed directly
2g
1g = 1V
0rpm >2000rpm
Torque
In-line torque
transducer
Force gauge
Measures shaft torque directly
Isolation amplifier
Current
Hall-Effect current transducer
Function and Remarks
Measures average shaft torque
indirectly
School of Electrical and Electronic Engineering
20 kHz
multiples of
kHz
multiples of
kHZ
below kHZ
Up to 50Nm
0.1V/Nm
Up to 100Nm
0.1V/Nm
© Dr. N. Ertugrul
Power systems applications :
Power systems cover a wide range of diverse
applications.
Application Areas:
Rotating electrical machines
Renewable energy systems
Power electronics
Transmission systems
Power system stability
Power system protection
Distributed generation systems
Smart grid
School of Electrical and Electronic Engineering
New efficient
hardware designs,
on-line and off-line
measurements, data
analysis and control !
© Dr. N. Ertugrul
Software tools used in Power Systems:
Some of the software tools
Matlab
Finite Element Analysis
PSIM
dSpace
.......
LabView
Major processes
Sensors and signal
conditioning
Measurements
Data storage and display
Signal analysis
Real-time control
Real-time monitoring
Power quality monitoring
Transformer condition monitoring
Rotating machine monitoring
(synchronous, wind )
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
Research and Trends
Five major LabView based applications are included:
Power quality monitoring in power systems
Condition monitoring of induction machines
A low-cost continuous condition monitoring unit with CompactRIO
PC based on-line monitoring system
Real time solar array monitoring in remote areas
Automated dynamometer test setup
Electrical machines tests
They have common characteristics, can easily be extended to
other applications and have room for improvement and
customization.
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
A. Power quality monitoring in power systems
“Although it is not easy to estimate accurately the exact cost of the pollution in the
quality of the power, poor power quality just in US causes about US$13.3 billion in
damage per year.”
An ideal three-phase ac supply consists of three phase voltages that are 120 degrees out of phase
and have identical magnitudes.
The three voltages should have sinusoidal waveform characteristic at constant frequency and should
be available continuously. Any diversion from these requirements to the level that has an adverse
effect on the electric consumers is considered as poor quality, "polluted", of power.
Voltage dips (sags), swells, interruptions, switching transients, harmonics, notches or flickers are
examples of the most frequent disturbances in power system networks.
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
B. Condition monitoring of induction machines
• Induction motors are the workhorses of industrialized
economies.
• It is estimated that in developed countries, they consume
nearly half of all electric energy generated.
• There are about ten million large (>80kW) induction motors
worldwide, which are generally very reliable and require
minimum maintenance.
However duty cycle, installation, manufacturing factors, and
environmental influences can deteriorate and reduce the
efficiency of these motors as in the other rotating machines.
Unexpected downtime which can significantly increase the
running cost or even be catastrophic in mission critical
applications. In other cases, the efficiency of the motors may
have been reduced due to the presence of various motor faults
but the motors may still operate. This kind of failure may have
a significant cost if not handled promptly and properly. For
example an induction machine, which its efficiency reduced
from 80% to 70%, would produce an additional electricity cost
of about 14% per year.
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
B. Condition monitoring of induction machines
A low-cost continuous condition monitoring unit with CompactRIO
•
Due to the development of low-cost compact reconfigurable devices, it has become possible to
develop a reconfigurable device to be used in on-line monitoring of induction motors.
• The idea is to develop a low-cost continuous monitoring unit, called an indicator unit, based on
low-cost sensors and a high performance standalone processing system, CompactRIO.
• The major benefits of the continuous monitoring process are: a reduction of the number of
unexpected failures due to fault detection at an earlier stage, and elimination of the need for
periodic condition monitoring inspections.
• For low and medium voltage motors the typical cost of a motor inspection is about A$500 per
motor, and it is common to have these tests on six monthly intervals giving an annual cost of
A$1000. Depending on the location, travel costs typically add about 50% to the testing cost
resulting in a rough annual inspection cost of about $1,500. This annual cost is of the order of the
initial target cost for the indicator unit.
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
B. Condition monitoring of induction machines
PC based on-line condition monitoring system
The shows data acquisition and processing main tasks in an advanced condition monitoring system. The simple LabVIEW based condition
monitoring devices may not cover all tasks shown in the figure, such as the diagnostic function, but it contain a data acquisition task with a
multiplexer, a sample and hold function, which can be built from a high speed amplifier and an Analog to Digital Converter (ADC).
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
B. Condition monitoring of induction machines
Sensor parameters and positions
Monitoring
Signals
Sensors
FFT Bandwidth
technique
Vibration
Acceleration Accelerometer
1-2 g
Velocity
10 Hz to 1 KHz
Displacemen
t
Stator
Current
Current
1,000Hz, 20th
Current
transducers: Hall- harmonics
Effect type or
Rogowski Coils
Stator
Voltage
Voltage
1,000Hz, 20th
Voltage
Transformers,
harmonics
Differential
Isolation
Amplifiers
Search coil or Hall mV range,
Flux
Magnetic
sensors (external or 1,000Hz, 20th
Leakage
Field
internal)
harmonics
Monitoring
School of Electrical and Electronic Engineering
Position
Motor drive end and
non drive end: axial,
radial-horizontal,
radial-vertical
Clipped to one, two or
three phase line supply
Clipped to one, two or
three phase of supply
Non drive-end or
motor out board
around the shaft
© Dr. N. Ertugrul
B. Condition monitoring of induction machines
Summary of sensor signal sampling information
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
C. Real time solar array monitoring system in remote areas
In solar based renewable energy systems, a number of single photo voltaic (PV) cells are
usually configured in series and/or in parallel to form an array to increase voltage and
current ratings. The PV arrays are also covered with some form protection material and are
assembled in a frame to increase their reliability against environmental factors and to
simplify installation. As these arrays operate in various regions and environmental
conditions, it is necessary to obtain their performances characteristics and to be able
accurately predict their energy output. Therefore, rapid improvements in the manufacture of
solar panels demand standardized tests to evaluate and compare solar panel performance.
As the energy output in a PV array depends upon the level solar insolation and the cell
temperature (which both is unpredictable) it is critical to develop an
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
D. Automated Dynamometer Test Setup
Electrical motor tests are one of the most time consuming and cumbersome tests due to their non linear
operating characteristics and the difficulties of accurate and repeatable loading. The developments in
PXI based d data acquisition systems and electronically controlled motor drives however, made such
tests relatively easy to implement.
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
E. Electrical machines tests
This test system is also developed to simplify the testing procedures of DC electrical machines
using the benefits of LabVIEW and associated data acquisition hardware.
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
Future research
• Real plug and play systems in power electronics
• High level modularity (such as general purpose inverter)
• Sensor integration and wireless communications
• Synchronised measurements in the main grids
• Educational/training tools using general purpose educational
•
base boards (Elvis): Automated wind and PV testing systems
USB based DAQ and integrated signal generation and
measurement
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul
Biography of Nesimi Ertugrul
He received the B.Sc. and M.Sc. degrees in Electrical and in Electronic and
Communication Engineering from the Istanbul Technical University, in 1985 and 1989
respectively, and received Ph.D. degree from the University of Newcastle upon Tyne,
UK, in 1993. Dr. Ertugrul joined the Adelaide University since 1994, where he is an
Associated Professor.
His research topics include rotor position sensorless operation of brushless permanent
magnet and switched reluctance motors, real-time control of electrical machines,
motion control, fault tolerant motor drives, condition monitoring, power quality and
power system monitoring, predictive maintenance, power electronics systems and
electric vehicles. He also engage in research in the development of interactive
computer-based teaching/learning systems involving object-oriented programming
and data acquisition.
Dr. Ertugrul a member of IEEE and the author of a book titled "LabVIEW for Electric
Circuits, Machines, Drives and Laboratories" Prentice Hall, 2002, and and serves on
the Editorial Advisory Board for the International Journal of Engineering Education
(IJEE).
School of Electrical and Electronic Engineering
© Dr. N. Ertugrul